Forest City Ratner Cos., developer of a controversial arena in Brooklyn, N.Y., finally broke ground on the project after years of delay, legal battles by residents fighting New York City’s use of eminent domain, a change of architect—from Frank Gehry to Ellerbe Becket and SHoP Architects—and two redesigns. The Barclays Center complex is planned as the future home of the National Basketball Association’s New Jersey Nets and as the centerpiece of a planned 22-acre sports village, which includes office buildings and housing. Site work has been under way since last fall, with construction set for completion in 2012.